Among various ultra-thin flat type display devices, which include a display screen having a thickness of several centimeters, a liquid crystal display (LCD) device can be widely used for notebook computers, monitors, aircraft, and etc. since it has advantages such as low power consumption and portability.
The LCD device includes lower and upper substrates facing each other at a predetermined interval therebetween, and a liquid crystal layer formed between the lower and upper substrates.
The lower substrate comprises a thin film transistor and a pixel electrode, and the upper substrate comprises a black matrix layer, a color filter layer and a common electrode.
The above LCD device includes various elements formed by repeated steps. Especially, a photolithography is used so as to form the elements in various shapes.
For the photolithography, it necessarily requires a mask of a predetermined pattern and a light-emission device, thereby increasing manufacturing cost. In addition, since the photolithography requires exposure and development, it causes a complicated process and an increasing manufacturing time.
To overcome these problems of the photolithography, a new patterning method has been developed, for example, a printing method. In the printing method, a predetermined material is coated on a printing roller, and then the printing roller is rotated on a substrate, to thereby form a predetermined pattern on the substrate.
Hereinafter, a related art printing method will be described with reference to the accompanying drawings.
FIGS. 1A to 1C are cross sectional views illustrating a printing method according to the related art.
As shown in FIG. 1A, first, a pattern material 20 is provided through a printing nozzle 10, and is coated on a printing roller 30. At this time, a blanket 35 is adhered onto an outer surface of the printing roller 30. That is, the pattern material 20 is coated onto the surface of the blanket 35.
The blanket 35 requires the good adherence to the printing roller 30, and requires the deformation resistance for the printing process. To this end, the blanket 35 is generally formed of Si-based resin.
Then, as shown in FIG. 1B, the printing roller 30 is rotated on a cliché plate 40 having concave 43 and convex 46 portions. That is, some pattern material 20a is transferred to the convex portions 46 of the cliché plate 40, and the remaining pattern material 20b is left on the surface of the printing roller 30, whereby a predetermined pattern 20b is formed on the blanket 35 of the printing roller 30 by the left pattern material 20b. 
As shown in FIG. 1C, as the printing roller 30 is rotated on a substrate 50, the predetermined pattern 20b of the printing roller 30 is transferred to the substrate 50.
Unlike the photolithography, the printing method requires no exposure and development. Thus, the printing method has the simplified process and decreased manufacturing cost, whereby the printing method is appropriate to the mass production of LCD device.
However, as repeating the patterning process by printing, the blanket 35 of the printing roller 30 is deformed due to the pattern material 20. That is, a solvent of the pattern material 20 dissolves the blanket 35, whereby the blanket 35 is swollen. Accordingly, it is impossible to realize a precise pattern due to the deformation of blanket 35.
That is, as shown in FIG. 2A, when the printing roller 30 having the blanket 35 coated with the pattern material 20 is rotated on the cliché plate 40 including the concave and convex portions 43 and 46, if the blanket 35 is swollen, the pattern material 20 contacts with the concave portions. In this case, as shown in FIG. 2B, the pattern material 20a and 20b is transferred to the concave portions 43 as well as the convex portions 46. Accordingly, the pattern material 20c being left on the blanket 35 of the printing roller 30 is not in a desired pattern. As a result, it is impossible to realize the precise pattern since ‘A’ of FIG. 2B has no pattern material.